Heat exchanger bundle



Feb. 21, 1967 H. w. ALLEIN 3,305,012

HEAT EXCHANGER BUNDLE Filed April 19, 1965 INVENTOR ATTORNEYS UnitedStates Patent This invention relates to tubular heat exchangers such asare in general use in refining and chemical industries and in steamgenerating plants, and has more particularly to do with the junction ofthe tubes with the tube sheets and the tube retainer members of suchexchangers.

, The invention constitutes a further novel development of the inventiondisclosed in the co-pending application of Celestin Victor Belanger,Serial No. 28,482, filed July 9, 1962, maturing as United States PatentNo. 3,181,606, of May 4, 1965, and owned by the assignee of the presentapplication. In that case, there was disclosed the concept of the use ofO-rings disposed in counterbores in the tube sheet, surrounding therespective tube ends, and sealing the relatively close tolerancesbetween the tube walls, the walls of the counterbores of the tubesheets, and the adjacent faces of the retainer members. As indicated inthat patent, these O-rings are of uniform cross section throughout theircircular extent, whatever the specific semicross-sectional configurationmight be, whether circular, square, quad, or other shape. The criterion,of course, is that the material from which the O-ring is made beelastic-and'capable of distortion or flowing within the recess orcounterbore in which it is positioned in order to effectively seal thefine tolerance clearances between the interfitting elements mentioned.

The general object of the invention is to provide novel and improvedsealed junctions for the tubes of exchanger bundles, which alfordsafeguards from deleterious results of any longitudinal displacement ofthe tubes as through expansion and contraction, and also which permitsthe continued utilization of used or worn tube sheets, thus effectingeconomics in manufacture and maintenance of the exchangers to whichthese novel provisions may be applied.

The invention, in its preferred embodiments, contemplates the provisionof annular sleeves, bushings, or rings preferably of a metal which isthe equivalent of that used in the manufacture of the tubing and tubesheets and I0- tary plates or fittings; these rings being closely fittedto the tube ends but relatively movable and disposed upon either or bothsides of the position of the elastic O-rings, depending upon theparticular condition present or circumstance to be overcome.

Other objects and features of novelty will be apparent from thefollowing specification when read in connection with the accompanyingdrawings in which certain embodiments of the invention are illustratedby way of example.

In the drawings:

FIGURE 1 is a fragmentary somewhat diagrammatic view in longitudinalsection through one of the tubes of an exchanger bundle, and suggestingthe tube end seating and sealing connections usable to preventdislocation of the seal at the tube ends upon the occurrence oflongitudinal expansion or contraction or displacement;

FIGURE 2 is a fragmentary sectional view of the lefthand end of such aninstallation showing the approximate position and condition of theO-ring upon the existence of predominant pressure from within the tubes;

FIGURE 3 is a view similar toFIGURE 1 and showing the condition of theO-rings at both ends of the tube upon the occurrence of predominantpressure externally of the tubes and with a tube which not only may havebeen subject to expansion or contraction conditions but may also beshorter than usual and displaced toward the left;

aaoaeiz Patented Feb. 21, 1967 FIGURE 4 is a view similar to theright-hand end portion of FIGURE 3 showing what would occur upon thedisplacement of a shortened tube in a left-hand direction without theprovision of the novel expansion ring;

FIGURE 5 is a fragmentary sectional view of the vicinity of theleft-hand end of a tube showing a connection comprising anotherembodiment of the invention in which a ring is employed as a tubecentering expedient; and

FIGURE 6 is a similar view showing the employment of two metal rings foraccomplishing both of the purposes toward which the invention isoriented.

In essence the basic provisions of the present invention involve the useof rigid cylindrical rings in association with elastic distortableO-rings within a counterbore constituting an enlargement of the holethrough the tube sheet through which the ends of the tubes extend, thisnovel provision being capable of accomplishing two functions eitherseparately or in combination.

FIGURE 1 of the drawings illustrates the embodiment in which the rigidring performs the function of preventing the destruction or loss of thesoft fiowable O-ring in cases where expansion or contraction or otherlongitudinal displacement of the tube might occur.

In this figure, one of the tubes of the tube bundle of an exchanger isindicated at 10 and its right and left-hand ends aredisposedrespectively through openings 11 and 12 in the oppositelypositioned tube sheets 15 and 16.

At 17 and 18 are shownconventional retainer members 'which are securedin juxta-position to the tube sheets 15 and 16 and may take any suitableor conventional form, whether as continuous plates substantiallyco-terminous "with the sheetsor as individual retainer elements eachassociated with one or more of the tubes of the bundle.

The retainer members are provided with holes 19 and 20 which must ofcourse be of somewhat smaller diameter than the external diameter of thetube 10 so that the tube may be properly retained within the bundle byabutment with the inward surface of the retainer members 17 and 18.

In the illustrative embodiment of FIGURE 1, the interfitting of the endof the tube 10 within the opening 11 is of a rather fine tolerance,generally to be expected in new and unworn constructions.

The tube 10 is shown in normal centered position where it is spacedslightly from the retainer members at each end, and fitted around theend portions of the tube 10 and disposed within the counterbores 22 and23 are the rigid cylindrical rings 25 and 26. The outer diameter of therings approximates the diameter of the counterbores and alfords a snugfit therebetween. Similarly, the inner diameters of-the rings 25 and 26fit snugly around the end portions of the tube 10.

I Inwardly .of the rings 25 and 26 and disposed within the counterboresarethe soft elastic deformable O-rings 30 and 31. These O-rings are ofsuch inner and outer diameters as to fit snugly between the wall of thecounterbores 22 and 23 and the outer walls of the ends of the tube 10,with either a barely tangential contact, or under a slight degree ofradial compression.

Although the O-rings 30 and 31 are shown as being of circularsemi-cross-section, they may be of any cross- ,sectional configurationsuitable for the structure contem- 3 adequately seals the junction at 40between the walls of the hole 11 in the tube sheet 15 and the outer wallof the tube 10. It will of course be understood that a similardistortion of the O-ring 31 at the opposite end of the bundle will occurunder these conditions.

Proceeding to FIGURE 3 of the drawings, it will be understood from thisshowing what occurs when the predominant fluid pressure is exteriorly ofthe tube system represented by the tube 10. Under such conditions, fluidpressure would be through the slight clearance between the walls of thehole 11 and the outer surface of the tube 10 into the counterbore 22 andserve to move and distort the elastic O-ring 30 as shown at theleft-hand end of FIGURE 3, so that the ring will flow into and seal thecorners represented at 45 and 46 and respectively located at thejunction of the outer surface of the rigid cylindrical ring 25 and theinner wall of the counterbore 22, and between the inner surface of thering 25 and the outer surface of the tube 10. In this situation theO-ring serves to seal two points of possible leakage of fluid pressure.

Under the influence of fluid pressure in the direction just described,the rigid rings 25 and 26 could move to the outer portions of thecounterbores 22 and 23 as suggested and abut the inner faces of theretainer elements 17 and 18, and an inspection of the right-hand end ofFIGURE 3 of the drawings will reveal how the rigid rings 25 and 26 actas expansion compensating elements when the tube 10 expands, contracts,or is displaced longitudinally of the bundle.

For this purpose, each of the rings 25 and 26 must 'be of a width oraxial dimension such that it is somewhat greater than any space 50 whichmight occur between one end of the tube 10 and the face of one of theretainer elements 17 or 18 when the tube is of a minimum length ascompared with the full distance between the inward faces of the elements17 and 18 and shifted laterally into abutment with one of these faces.

In FIGURE 4 there is illustrated what would occur under such conditionsof contraction, expansion, or displacement were the rings 25 and 26 notprovided. In this figure corresponding parts at the right-hand end ofthe bundle are indicated by similar reference characters as in FIGURE 3but with a prime added. As in the case of FIGURE 3, the pressure isexternally of the tubes 10' and in the absence of the rigid ring 26, theO-ring 31' is shown in process of flowing around the end of the tube 10,and under a relatively great external pressure the tube would bedistorted and damaged and squirted or blown out through the tube 10' orthrough the opening 20' in the retainer element 18'. The provisionillustrated in FIGURE 3 of the drawings in accordance with theprinciples of the present invention precludes such damage or destructionof the bundle as suggested in FIGURE 4.

In FIGURE there is illustrated a further function and utility of thebroad principles of the present invention. This embodiment isparticularly applicable to making it possible to greatly extend the lifeof tube sheets of an exchanger even if the opening 11 into which thetube fits is enlarged as indicated at 11A in FIGURE 5. These old wornsheets may be employed by deepening the counterbore 22, if necessary,and inserting the rigid cylindrical ring 60 within the counterboreinwardly of the sealing O-ring 30.

In FIGURE 5 the arrangement is similar to that shown in FIGURE 5 of theBelanger patent where the opening 19 in the retainer member 17 issomewhat enlarged as at 19A, the enlarged counterbore portion 19A beingof a diameter to snugly receive the extreme end portion of the tube 10.

The rigid cylindrical ring 60, which in accordance with its function nowbeing described, may be called a centering ring, has an outer diameterapproximating the diameter of the counterbore 22 and an inner diameterapproximating the outer diameter of the tube and serves to center thetube properly regardless of the wear which might have occu red to thbore 1 A- In this embodiment the O-ring very obviously performs theusual sealing function in whatever direction the preponderance of fluidpressure exerts itself. If the pressure is from without the tube system,exerted through the clearance 11A and around the ring 60, the O-ringwill seal the corner 65 between the surfaces of the sheet 15 and theretainer 17 and the corner 66 between the outer surface of the tube 10and the counterbore 19A of the retainer 17. Under a predominance offluid pressure from within the tube system the O-ring would of coursemove into contact with the rigid centering ring 60 and seal the corner68 between the wall of the counterbore 22 and the outer surface of thering 60, and the corner 69 between the inner surface of the ring 60 andthe outer surface of the tube 10.

Now in order to provide against both deleterious eventualitiesdescribed, two rigid cylindrical rings may be provided within thecounterbore of the tube sheet, one upon either side of the O-ring. Thisarrangement is illustrated in FIGURE 6 of the drawings where the tube 10enters the possibly enlarged passageway 11A and passes through thecounterbore 22 in the tube sheet 15. The retainer member 17 is providedwith the usual opening 19 which in this instance is not counterbored andis of a smaller diameter than the outside diameter of the tube 10. TheO-ring 30 is disposed between the rigid cylindrical expansion ring 25and the inwardly disposed rigid cylindrical centering ring 60 and it isquite obvious that upon the occurrence of a predominance of fluidpressure either internally or externally of the tube system the O- ringwill move toward one or the other of the rings 25 and 60 and perform thesealing functions as described in the case of the use of the separaterings.

From the above, numerous advantages of the present invention will beapparent. I

In connection with the utilization of the rigid cylindrical rings ascentering devices as in FIGURES 5 and 6 it can be pointed out that tubesheets of an average heat exchanger cost somewhere in the neighborhoodof $2,500.00 a pair and many hundreds of them are discarded every day inthe chemical and refining industries. The considerable economy effectedby the present invention is thus illustrated when it is realized thatthe metal centering rings can be furnished at an average cost of aboutthree cents apiece. These rings may be made of material of durabilityappropriate to the function to be performed by the exchanger but wouldusually be made of metal compatible with the metal of the various partsof the tube bundle, for example, of brass, copper, or steel.

Previous attempts to accommodate tubes to worn tube sheets have usuallyinvolved the use of expanders for the tubes or rolling the tubes to fitthe enlarged worn holes in the sheets, but it was found that each timethe tubes were replaced, the expanders increased the diameter of thetube hole in the sheet to a point where the tubes could not be rolled tofit and were too large for the O-rings to seal the opening between thetube and the tube sheet.

In the utilization of the rigid cylindrical ring as an expansionaccommodating element as in FIGURES 1, 2, 3, and 6 of the drawings, itwill be noted that the counterboring in the retainer elements, as at19A, can be eliminated, thus efiecting further economies inconstruction.

It is understood that various changes and modifications may be made inthe embodiments illustrated and described herein without departing fromthe scope of the invention as defined by the following claims.

Having thus described the inventon, what is claimed as new and desiredto be secured by Letters Patent is:

1. In a heat exchanger device of the class described, which includeswithin its usual assembly of parts: a shell; a tube bundle comprisingtubes, tube sheets, and retainer plates, said tubes having endsextending through said tube sheets, and said retainer plates applied tothe outer surfaces of said tube sheets; and fluid inlet and outletconnections: the improvement which comprises the tube and tube sheetconnection whereinthe tube sheet is provided with a hole passingtherethrough into which an end of the tube extends, a counterboreextending into said tube sheet from the side opposite to that into whichthe tube extends, said counterbore constituting a coaxial enlargement ofsaid hole and having a cylindrical Wall surrounding said tube end; arigid cylindrical ring disposed within said counter bore and having anoutside diameter providing a snug fit of small tolerance within the wallof said coutnerbore and an inside diameter providing a similarly snugfit onto the tube end; and an elastic deformable O-ring disposed withinsaid counterbore alongside of said rigid cylindrical ring and of athickness for contact of its outer and inner diametrical boundariesrespectively with the cylindrical wall of the counterbore and the outersurface of the tube end in normal relaxed condition, said counterborebeing of greater axial length than that of said rigid ring and saiddeformable O-ring, whereupon upon subjection of the bundle to apreponderance of fluid pressure upon either the inside or the outside ofthe tubes, the O-ring will effectively seal the junctions of thesurfaces concerned whether of the tube, the tube sheet, or the rigidcylindrical ring.

2. The device as set forth in claim 1 in which said retainer member issecured in closed proximity to the outside face of the tube sheet and isprovided with an opening substantially coaxial with said tube and of adiameter less than the outside diameter of the tube, wherebycommunication is established from the inside of the tube through saidretainer plate; the O-ring being positioned exteriorly of the said rigidcylindrical ring within said counterbore and serving also to seal offsmall tolerance clearances between the tube and said retainer member andbetween the tube sheet and said retainer member.

3. The device as set forth in claim 1 in which said retainer member issecured in close parallel proximity to the outside face of the tubesheet at each end of the bundle and each retainer member is providedwith an opening substantially coaxial with said tube and of a diameterless than the outside diameter of the tube, whereby communication isestablished from the inside of the tube through said retainer member;the O-ring being positioned within said counterbore interiorly of saidrigid cylindrical ring; and the. difference between the minimum lengthof the tube and the maximum longitudinal distance between the retainerplates at the opposite ends of the bundle being less than the axialdimension of one of said rigid cylindrical rings, whereby distortion andextrusion of an O-ring around the end of the tube within saidcounterbore under pressure from without the tube system is prevented.

4. The device as set forth in claim 2 in which the hole in the tubesheet through which the tube extends is of greater diameter than theoutside diameter of the tube, as when a used worn tube sheet is reboredfor continued use, whereby said rigid cylindrical ring acts as a tubecentering means as well as a renewed sealing seat for said O-ring.

5. The device as set forth in claim 2 in which one of said rigidcylindrical rings is provided upon each side of the O-ring Within saidcounterbore, each cylindrical ring acting as an O-riug seat around theouter surface of the tube.

6. The device as set forth in claim 5 in which the hole in the tubesheet through which the tube extends is of greater diameter than thediameter of the tube, as when a used worn tube sheet is re-bored forcontinued use, whereby the inner one of said rigid cylindrical ringsacts as a tube centering means as well as a renewed sealing seat forsaid O-ring, and the outer one of said rings functions as an expansionring to prevent loss or damage to the O-ring due to any longitudinaldisplacement of the tube.

References Cited by the Examiner UNITED STATES PATENTS 2,488,807 11/1949Currie 165-82 2,635,931 4/1953 May 2.85

2,904,315 9/1959 Pennella l-82 ROBERT A. OLEARY, Primary Examiner.

C. SUKALO, Assistant Examiner.

1. IN A HEAT EXCHANGER DEVICE OF THE CLASS DESCRIBED, WHICH INCLUDES WITHIN ITS USUAL ASSEMBLY OF PARTS: A SHELL; A TUBE BUNDLE COMPRISING TUBES, TUBE SHEETS, AND RETAINER PLATES, SAID TUBES HAVING ENDS EXTENDING THROUGH SAID TUBE SHEETS, AND SAID RETAINER PLATES APPLIED TO THE OUTER SURFACES OF SAID TUBE SHEETS; AND FLUID INLET AND OUTLET CONNECTIONS: THE IMPROVEMENT WHICH COMPRISES THE TUBE AND TUBE SHEET CONNECTION WHEREINTHE TUBE SHEET IS PROVIDED WITH A HOLE PASSING THERETHROUGH INTO WHICH AN END OF THE TUBE EXTENDS, A COUNTERBORE EXTENDING INTO SAID TUBE SHEET FROM THE SIDE OPPOSITE TO THAT INTO WHICH THE TUBE EXTENDS, SAID COUNTERBORE CONSTITUTING A COAXIAL ENLARGEMENT OF SAID HOLE AND HAVING A CYLINDRICAL WALL SURROUNDING SAID TUBE END; A RIGID CYLINDRICAL RING DISPOSED WITHIN SAID COUNTERBORE AND HAVING AN OUTSIDE DIAMETER PROVIDING A SNUG FIT OF SMALL TOLERANCE WITHIN THE WALL OF SAID COUNTERBORE AND AN INSIDE DIAMETER PROVIDING A SIMILARLY SNUG FIT ONTO THE TUBE END; AND AN ELASTIC DEFORMABLE O-RING DISPOSED WITHIN SAID COUNTERBORE ALONGSIDE OF SAID RIGID CYLINDRICAL RING AND OF A THICKNESS FOR CONTACT OF ITS OUTER AND INNER DIAMETRICAL BOUNDARIES RESPECTIVELY WITH THE CYLINDRICAL WALL OF THE COUNTERBORE AND THE OUTER SURFACE OF THE TUBE END IN NORMAL RELAXED CONDITION, SAID COUNTERBORE BEING OF GREATER AXIAL LENGTH THAN THAT OF SAID RIGID RING AND SAID DEFORMABLE O-RING, WHEREUPON UPON SUBJECTION OF THE BUNDLE TO A PREPONDERANCE OF FLUID PRESSURE UPON EITHER THE INSIDE OR THE OUTSIDE OF THE TUBES, THE O-RING WILL EFFECTIVELY SEAL THE JUNCTIONS OF THE SURFACES CONCERNED WHETHER OF THE TUBE, THE TUBE SHEET, OR THE RIGID CYLINDRICAL RING. 